reproduce (this is a W=1 build):
        # https://github.com/avpatel/linux/commit/0ae68ded2664be53f2e34c2be7b639b6b2ef711f
        git remote add avpatel https://github.com/avpatel/linux.git
        git fetch --no-tags avpatel riscv_iommu_irqbypass_v2
        git checkout 0ae68ded2664be53f2e34c2be7b639b6b2ef711f

        # install riscv cross compiling tool for clang build
        # apt-get install binutils-riscv64-linux-gnu
        # clang-23 might not be officially released. Try a lower version if installation fails.
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-23 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-23 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=riscv SHELL=/bin/bash arch/riscv/kvm/ drivers/iommu/riscv/